The invention relates to a carousel for treating hollow containers, comprising several identical treatment stations, each of them designed to handle one or more hollow containers, and of the type in which, for at least one stage of the treatment, the treatment station is connected to a pressure source, by means of a sealed swivel coupling.
In certain applications, the target is that at each instant, only one station will be connected to a given pressure source, in order to guarantee, for example, a given level of pressure at the relevant treatment station. That is especially true when the pressure source available is only able to furnish a limited amount of fluid at the desired pressure. Such a situation is found for example, when the target pressure level is lower than atmospheric pressure.
With an eye on profitable industrial utilization, in all cases, one seeks to obtain from the in machine, the best possible performance level, while using the least expensive means possible.
Increasing the number of stations is the first draft solution to this problem. However, in this case, each treatment station on the carousel is to be found at a particular stage of the treatment process, specifically, within the framework of the series of steps, during which there occur continuous variations in the characteristic parameters of the treatment process.
This is notably the case for pumping in steps, because a vacuum cannot be created instantaneously. Hence, each step has a duration, and in that time, the pressure level is continuously evolving.
If the number of stations is significant enough, it is possible that two consecutive stations will be so close together, that they will be carrying out the same stage, but at different steps of that stage. The two stations are therefore at different pressure levels.
Now in this case, it is not possible to connect the two stations to the same pressure source, because the pressure in the two consecutive stations would tend to come into equilibrium almost instantaneously, as soon as the second of the two stations would be connected to the source. The first station would therefore lose almost all the benefit accrued from having carried out the steps of the process up to that point.
Document U.S. Pat. No. 5,585,066, describes a machine for blow molding plastic receptacles. This machine involves a distributor of fluid pressure, which is provided with a stationary crown, which has in it, on a transverse face, two concentric annular grooves of different diameters. Each of these two grooves is divided into a certain number of sections, which are each connected to sources with a different pressure level, or even possibly to the atmosphere. The machine described is not designed to work with only one treatment station. It can be seen that the distributor, moreover, includes a rotating device, which is provided with two communication ports, each of which must rotate relative to one of the grooves, in line respectively with the sections of the corresponding groove. The distributor described, permits the connection of the treatment station with a primary high-pressure air source, of about 6 bars, and to a second source of air at low pressure, of about 3 bars, or to the atmosphere.
It can be seen that the machine described does not solve the problem of operating several stations, when the target is that no more than one station, at any instant, will be connected to one given pressure source.
In effect, in such a case, it would be necessary to provide for the relevant section of the groove, a sufficient angular separation that would correspond to the duration of the step under consideration.
Now, in order to have only one station connected to the pressure source, which is connected to the section of the groove, one would be obligated to provide for the pressure intake ports connected to two consecutive stations, to be separated by an angle at least equal to the angular separation of the section. Thus, a limit would be imposed on the number of stations, which could be installed on the carousel.
The only solution which a skilled technician could have found to this problem, based on current state of the art, would be to significantly increase the power of the source, in such a way that the duration of the step might be less than the time for two consecutive stations to pass the same point. This solution would, therefore, have led to an exponential growth in the cost of the pumps put into operation, all the more since it would be necessary to take into account the added losses of charges, which accompany the necessary pumping increase.
Therefore, this invention has as its purpose, to propose a machine which might involve a significant number of stations, all the while guaranteeing that one pressure source would be connected, at any given instant, to only one treatment station.
To that end, the invention proposes a machine of the type described above, but characterized by the fact that, for the said stage, the machine would have at least two independent and equivalent sources of pressure, in that the stations are distributed in such a way, and into just as many groups as the machine has sources, in that the means of distribution are such, that each source is associated with a distinct group.
According to other characteristics of the invention:
the means of distribution are such that, at each instant, one of the said sources is connected to only one station;
the means of distribution are such, that at least one station of one group can be connected to its associated source, at the same time as at least one station of another group is connected to its own relevant associated source;
the swivel coupling involves as many paths as the machine has sources for separately feeding groups of stations, and the means of distribution involves, downstream of the swivel coupling, a means of individual speed control associated with each station.
the swiveled sealed coupling is realized in the form of a rotating distributor involving two co-axial crowns, one stationary, and the other rotating, which are in sealed contact with each other, by adjacent contact surfaces; the rotating crown has communication ports, each one of which is connected to one station, which are distributed in at least as many series, as the machine has sources for the said stage, and have their endpoint on the contact surface of the rotating crown; all the ports of one same series correspond to stations of one same group, and follow the same trajectory; the ports of two different series follow different trajectories; the stationary crown has light sources which are connected to a pressure source, and all of them terminate on the contact surface of the stationary crown in such a way, as to find themselves on the trajectory of a series of ports of the rotating crown, so that one station is connected to one pressure source, when the corresponding port finds itself to be in line with the relevant light; the stationary crown involves at least as many distinct series of at least one light, as the number of the series of ports, and two sources of pressure which pertain to the same stage, are each connected to one light of the two distinct series of lights of the stationary crown:
the ports of all the stations of one same group belong to the same series;
the contact surfaces of the two crowns are annular faces, perpendicular to the axis of rotation of the carousel;
the ports of one same series are designed in a circle, and two series of ports are designed as two circles with different diameters;
the ports of one same series are angularly distributed in a regular manner, around the axis of rotation of the carousel, and the ports of two different series, involving the same number of ports, and angularly intercalated;
the lights which pertain to two independent and equivalent pressure sources, and utilized for the above-cited stage, are fitted at the same angular displacement, and on different diameters, corresponding respectively, to the diameters of circles along which the series of ports corresponding to the said sources are fitted;
two consecutive ports of one same series are separated by an angular displacement at least equal to the extent of angular displacement of the corresponding light of the said series;
the treatment includes a second stage, during which the treatment stations are connected by means of a rotating distributor, with secondary sources of pressure for reaching a second pressure level, the stationary crown also has, in the prolongation of each of the primary lights, secondary lights which are each connected to one of the secondary sources of pressure, and the two lights associated with one same series of ports are separated by an angle which prevents the simultaneous connection of one port with two lights;
the sources of pressure have an internal pressure lower than atmospheric;
treatment includes a stage in which a cold, low-pressure plasma is created, for the purpose of coating the hollow container; this includes at least one pumping stage for lowering the internal pressure of the treatment station, and the pumping step is achieved by utilizing at least two pumps, each one of which is associated with one distinct group of stations, in conformity with the other characteristics given above.
The invention also proposes a rotating distributor for a carousel machine to treat hollow containers, the machine involving several identical treatment centers, each one designed to handle at least one hollow container, of the type in which the distributor includes two coaxial crowns, the one stationary, and the other rotating, which are in contact with each other in a sealed manner, through the contact of adjacent surfaces, of the type in which the rotating crown includes some communication ports, each of which are designed to be connected to a station, and which open out into the contact surface of the rotating crown, of the type in which the stationary crown includes at least one light whose purpose is to link up with one of the machine""s pressure sources, and which terminates at the contact surface of the stationary crown, in such a way as to find itself on the same trajectory as the ports of the rotating crown, in such a way that one station is connected to the pressure source while the corresponding port is found in line with the light, all of this characterized by the ports of rotating crown being distributed in at least two series, where the ports of one same series follow the same trajectory, while the ports of two different series follow different trajectories; in that the stationary crown includes as many distinct series, of at least one light, as the number of the series of ports, each of the lights being situated on the trajectory of one of the series of ports, and in that the two sources of independent and equivalent pressure are each connected to one light of the two distinct series.
According to still other characteristics of the invention""s distributor:
the contact surfaces of the two crowns are annular surfaces, perpendicular to the axis of rotation of the carousel;
the ports of one same series are designed in a circle, and two series of ports are designed as two circles with different diameters;
the ports of one same series are angularly distributed, in a regular manner, around the axis of rotation of the carousel, and the ports of two different series, involving the same number of ports, are angularly intercalated;
the lights which pertain to two pressure sources, utilized for the above-cited stage, are fitted on the same angular displacement, and on different diameters corresponding, respectively, to the diameters of circles according to the series of ports to which said sources correspond;
two consecutive ports of one same series are separated by an angular displacement at least equal to the extent of angular displacement of the corresponding light of the said series of ports;
the stationary crown includes, for each of the series of lights, at least two lights, one being the extension of the other, and two lights of the same series are separated by an angle that prevents a port from being connected to two lights at the same time.